Increased miR-222 in H. pylori-associated gastric cancer correlated with tumor progression by promoting cancer cell proliferation and targeting RECK. FEBS Lett. 2012;586:722-728. [PMID: 22321642 DOI: 10.1016/j.febslet.2012.01.025]

Circulating miR-222 in plasma and its potential diagnostic and prognostic value in gastric cancer

Previous studies have revealed the significance of circulating microRNAs as biomarkers for cancers. The aim of this study was to detect the levels of circulating microRNA-222 (miR-222) in plasma of gastric cancer (GC) patients and evaluate its diagnostic and prognostic value. Levels of circulating miR-222 were detected by using qRT-PCR in plasma of 114 GC patients, 36 chronic atrophic gastritis (CAG) patients and 56 healthy controls. The result showed that the expression of circulating miR-222 in plasma was significantly upregulated in GC compared with CAG and healthy controls (all at P < 0.001). And its high level was significantly correlated with clinical stages (P < 0.001) and lymph nodes metastasis (P = 0.009). The receiver operating characteristics (ROC) curve analyses revealed that miR-222 had considerable diagnostic accuracy, yielded an AUC (the areas under the ROC curve) of 0.850 with 66.1 % sensitivity and 88.3 % specificity in discriminating GC from healthy controls. Moreover, Kaplan-Meier analysis demonstrated a correlation between increased circulating miR-222 level and reduced disease-free survival (P = 0.016) and overall survival (P = 0.012). In multivariate analysis stratified for known prognostic variables, circulating miR-222 was identified as an independent prognostic marker. In conclusion, our findings suggested that circulating miR-222 in plasma might be a potential and useful noninvasive biomarker for the early detection and prognosis of GC.

MicroRNAs in the interaction between host and bacterial pathogens

MicroRNAs (miRNAs) are small non-coding RNAs with a central role in the post-transcriptional control of gene expression, that have been implicated in a wide-range of biological processes. Regulation of miRNA expression is increasingly recognized as a crucial part of the host response to infection by bacterial pathogens, as well as a novel molecular strategy exploited by bacteria to manipulate host cell pathways. Here, we review the current knowledge of bacterial pathogens that modulate host miRNA expression, focusing on mammalian host cells, and the implications of miRNA regulation on the outcome of infection. The emerging role of commensal bacteria, as part of the gut microbiota, on host miRNA expression in the presence or absence of bacterial pathogens is also discussed.

MicroRNA and signaling pathways in gastric cancer

MicroRNAs (miRNAs) function as either oncogenes or tumor suppressors by inhibiting the expression of target genes, some of which are either directly or indirectly involved with canonical signaling pathways. The relationship between miRNAs and signaling pathways in gastric cancer is extremely complicated. In this paper, we determined the pathogenic mechanism of gastric cancer related to miRNA expression based on recent high-quality studies and then clarified the regulation network of miRNA expression and the correlated functions of these miRNAs during the progression of gastric cancer. We try to illustrate the correlation between the expression of miRNAs and outcomes of patients with gastric cancer. Understanding this will allow us to take a big step forward in the treatment of gastric cancer.

MiR-25 promotes gastric cancer cells growth and motility by targeting RECK

Gastric cancer (GC) is the second leading cause of cancer-related death worldwide. Recently, accumulating evidence suggests that microRNAs (miRNAs) play prominent roles in tumorigenesis and metastasis. Here, we confirmed that miR-25 was significantly increased in human GC tissues and cell lines. Forced expression of miR-25 remarkably enhanced cell proliferation, migration, and invasion in GC cells, whereas inhibition of miR-25 by inhibitor caused significant suppression of proliferation and significant increase of apoptosis. Moreover, inhibition of miR-25 significantly decreased migration and invasion of GC cells. Finally, reversion-inducing-cysteine-rich protein with kazal motifs (RECK) was found to be a target of miR-25. Overexpression of RECK could significantly reverse the oncogenic effect of miR-25. Taken together, miR-25 might promote GC cells growth and motility partially by targeting RECK.

miR-375 inhibits Helicobacter pylori-induced gastric carcinogenesis by blocking JAK2-STAT3 signaling

Gastric cancer remains the second leading cause of cancer-related deaths worldwide. Although Helicobacter pylori (H. pylori) is considered to be a critical risk factor, the molecular mechanisms underlying H. pylori-induced gastric carcinogenesis are still poorly defined. Recently, accumulating studies have revealed that microRNAs play key roles in development, differentiation, immune regulation, and even carcinogenesis. This study was performed to explore the mechanism of microRNA-375 (miR-375) in H. pylori promotion of gastric carcinogenesis. It was shown that miR-375 was down-regulated in response to H. pylori infection in gastric epithelial cell lines; this finding was quite opposite to the expression patterns of pro-inflammatory cytokines observed in a co-culture cell model. Moreover, the ectopic expression of miR-375 aggravated cell proliferation and migration. It was further observed that Janus kinase 2 (JAK2) was a bona fide target of miR-375 and further activated signal transducer and activator of transcription 3 (STAT3) and other downstream target molecules. Both gain-of-function and loss-of-function experiments showed that decreased miR-375 expression could mimic the oncogenic effects of the JAK2-STAT3 pathway. In addition, pretreatment with siRNAs targeting JAK2 prevented gastric epithelial cells from increasing proliferation and migration even in response to H. pylori infection. For the first time, our results demonstrate that the JAK2-STAT3 pathway regulated by miR-375 is involved in H. pylori-induced inflammation; this pathway promotes neoplastic transformation by affecting the expression of BCL-2 and TWIST1, hence offering a potential therapeutic target for inflammation-related cancers, especially those related to H. pylori.

Role of microRNAs in gastric cancer

Although gastric cancer (GC) is one of the leading causes of cancer-related death, major therapeutic advances have not been made, and patients with GC still face poor outcomes. The prognosis of GC also remains poor because the molecular mechanisms of GC progression are incompletely understood. MicroRNAs (miRNAs) are noncoding RNAs that are associated with gastric carcinogenesis. Studies investigating the regulation of gene expression by miRNAs have made considerable progress in recent years, and abnormalities in miRNA expression have been shown to be associated with the occurrence and progression of GC. miRNAs contribute to gastric carcinogenesis by altering the expression of oncogenes and tumor suppressors, affecting cell proliferation, apoptosis, motility, and invasion. Moreover, a number of miRNAs have been shown to be associated with tumor type, tumor stage, and patient survival and therefore may be developed as novel diagnostic or prognostic markers. In this review, we discuss the involvement of miRNAs in GC and the mechanisms through which they regulate gene expression and biological functions. Then, we review recent research on the involvement of miRNAs in GC prognosis, their potential use in chemotherapy, and their effects on Helicobacter pylori infections in GC. A greater understanding of the roles of miRNAs in gastric carcinogenesis could provide insights into the mechanisms of tumor development and could help to identify novel therapeutic targets.

miR-20b suppresses Th17 differentiation and the pathogenesis of experimental autoimmune encephalomyelitis by targeting RORγt and STAT3

The differentiation and function of IL-17-producing Th17 cells are tightly regulated by specific transcription factors and cytokines, which are the key participants in the pathogenesis of multiple sclerosis (MS) and experimental autoimmune encephalomyelitis (EAE). Although specific miRNAs have been shown to be involved in the development of MS and EAE, the potential role of miRNAs in the context of Th17-driven autoimmunity is just beginning to be clarified. miR-20b has been reported as a downregulated miRNA in blood cells of MS patients. In this report, it was further studied in greater detail because we found it was significantly downregulated during EAE, and, in the in vitro differentiation model, Th17 cells had lower expression of miR-20b than did Th1, Th2, or inducible T regulatory cells. Ectopic expression of miR-20b repressed Th17 differentiation in vitro. Using lentiviral vectors for miR-20b overexpression in vivo, we demonstrated that overexpression of miR-20b led to decreased Th17 cells and reduced severity of EAE. Furthermore, we also identified both RAR-related orphan receptor γt and STAT3 as potential targets of miR-20b. Finally, we confirmed that the mild disease severity and low number of Th17 cells in LV-miR-20b-infected mice were largely reversed by coinfection of these mice with lentivirus-expressing RAR-related orphan receptor γt or STAT3 3'-untranslated regions. Taken together, our results contribute to the importance of miRNAs in Th17 differentiation and pathogenesis of MS and EAE.

Influence of bacteria on epigenetic gene control

Cellular information is inherited by daughter cells through epigenetic routes in addition to genetic routes. Epigenetics, which is primarily mediated by inheritable DNA methylation and histone post-translational modifications, involves changes in the chromatin structure important for regulating gene expression. It is widely known that epigenetic control of gene expression plays an essential role in cell differentiation processes in vertebrates. Furthermore, because epigenetic changes can occur reversibly depending on environmental factors in differentiated cells, they have recently attracted considerable attention as targets for disease prevention and treatment. These environmental factors include diet, exposure to bacteria or viruses, and air pollution, of which this review focuses on the influence of bacteria on epigenetic gene control in a host. Host-bacterial interactions not only occur upon pathogenic bacterial infection but also continuously exist between commensal bacteria and the host. These bacterial stimuli play an essential role in various biological responses involving external stimuli and in maintaining physiological homeostasis by altering epigenetic markers and machinery.

Helicobacter pylori infection: host immune response, implications on gene expression and microRNAs

Helicobacter pylori (H. pylori) infection is the most common bacterial infection worldwide. Persistent infection of the gastric mucosa leads to inflammatory processes and may remain silent for decades or progress causing more severe diseases, such as gastric adenocarcinoma. The clinical consequences of H. pylori infection are determined by multiple factors, including host genetic predisposition, gene regulation, environmental factors and heterogeneity of H. pylori virulence factors. After decades of studies of this successful relationship between pathogen and human host, various mechanisms have been elucidated. In this review, we have made an introduction on H. pylori infection and its virulence factors, and focused mainly on modulation of host immune response triggered by bacteria, changes in the pattern of gene expression in H. pylori-infected gastric mucosa, with activation of gene transcription involved in defense mechanisms, inflammatory and immunological response, cell proliferation and apoptosis. We also highlighted the role of bacteria eradication on gene expression levels. In addition, we addressed the recent involvement of different microRNAs in precancerous lesions, gastric cancer, and inflammatory processes induced by bacteria. New discoveries in this field may allow a better understanding of the role of major factors involved in the pathogenic mechanisms of H. pylori.

MiR-96 downregulates RECK to promote growth and motility of non-small cell lung cancer cells

MicroRNAs play critical roles in the development and progression of non-small cell lung cancer (NSCLC). miR-96 acts as an oncogene in some malignancies, while its role in NSCLC is unclear. Here, we validated that miR-96 was significantly increased in both human NSCLC tissues and cell lines. Inhibition of miR-96 expression remarkably reduced cell proliferation, colony formation, migration, and invasion of NSCLC cells. Reversion-inducing-cysteine-rich protein with kazal motifs (RECK) was identified as a target of miR-96 in NSCLC cells. In addition, the expression of RECK was found to be negatively correlated with the expression of miR-96 in NSCLC tissues. Our data suggest that miR-96 might promote the growth and motility of NSCLC cells partially by targeting RECK.

Posttranscriptional deregulation of Src due to aberrant miR34a and miR203 contributes to gastric cancer development

Gastric cancer remains the main cause of cancer death all around the world, and upregulated activation of the nonreceptor tyrosine kinase c-SRC (SRC) is a key player in the development. In this study, we found that expression of Src is also increased in clinical gastric cancer samples, with the protein level increased more significantly than that at the RNA level. Further study revealed that miR34a and miR203, two tumor suppressive miRNAs, inversely correlate with the expression of Src. Restoration of miR34a and miR203 decreased Src expression in gastric cancer cell lines, which in turn inhibited cell growth and cell migration. In summary, our study here revealed that posttranscriptional regulation of Src contributes to the deregulated cell growth and metastasis in gastric cancer, and targeting Src by miR34a or miR203 mimics would be a promising strategy in therapy. [BMB Reports 2013; 46(6): 316-321]

miR-96 promotes tumor proliferation and invasion by targeting RECK in breast cancer

microRNAs (miRNAs) are small non-coding RNAs that post-transcriptionally regulate gene expression in diverse biological processes. The aim of the present study was to investigate the expression pattern of miR-96 in breast cancer and its biological role in tumor progression. The expression levels of miR-96 were analyzed in 38 breast cancer specimens and 6 breast cancer cell lines by quantitative reverse-transcription polymerase chain reaction (qRT-PCR). The effect of miR-96 on proliferation was evaluated by MTT assays, and cell migration and invasion were evaluated by transwell assays in MDA-MB-231 human breast cancer cells. Luciferase reporter assays were performed to validate the regulation of a putative target of miR-96. The effects of modulating miR-96 on endogenous levels of this potential target were subsequently confirmed via qRT-PCR and western blot analysis. We found that expression of miR-96 was commonly upregulated in breast cancer cells and breast cancer specimens when compared with that in non-malignant breast epithelial cells and adjacent normal tissues. Ectopic expression of miR-96 promoted cellular proliferation, migration and invasion of breast cancer cells, whereas inhibition of miR-96 suppressed those functions. Luciferase assays revealed that miR-96 directly bound to the 3'-untranslated region (3'-UTR) of RECK. qRT-PCR and western blot analysis confirmed that miR-96 regulated the expression of RECK both at the mRNA and protein levels. Knockdown of RECK expression in MDA-MB-231 cells by siRNA significantly promoted cell proliferation, migration and invasion. Collectively, miR-96 was significantly upregulated in breast cancer. our data also delineate the molecular pathway by which miR-96 promotes breast cancer proliferation, migration and invasion. Our findings may have important implications for the treatment of breast cancer.

Inhibition of miR-92b suppresses nonsmall cell lung cancer cells growth and motility by targeting RECK

microRNAs play critical roles in the progression and metastasis of nonsmall cell lung cancer (NSCLC). miR-92b acts as an oncogene in some malignancies; however, its role in NSCLC remains poorly understood. Here, we found that miR-92b was significantly increased in human NSCLC tissues and cell lines. Inhibition of miR-92b remarkably suppressed cell proliferation, migration, and invasion of NSCLC cells. Reversion-inducing-cysteine-rich protein with kazal motifs (RECK) was identified to be a target of miR-92b. Expression of miR-92b was negatively correlated with RECK in NSCLC tissues. Collectively, miR-92b might promote NSCLC cell growth and motility partially by inhibiting RECK.

MRNA and miRNA expression patterns associated to pathways linked to metal mixture health effects

Metals are a threat to human health by increasing disease risk. Experimental data have linked altered miRNA expression with exposure to some metals. MiRNAs comprise a large family of non-coding single-stranded molecules that primarily function to negatively regulate gene expression post-transcriptionally. Although several human populations are exposed to low concentrations of As, Cd and Pb as a mixture, most toxicology research focuses on the individual effects that these metals exert. Thus, this study aims to evaluate global miRNA and mRNA expression changes induced by a metal mixture containing NaAsO2, CdCl2, Pb(C2H3O2)2·3H2O and to predict possible metal-associated disease development under these conditions. Our results show that this metal mixture results in a miRNA expression profile that may be responsible for the mRNA expression changes observed under experimental conditions in which coding proteins are involved in cellular processes, including cell death, growth and proliferation related to the metal-associated inflammatory response and cancer.

Role of microRNA-mediated MMP regulation in the treatment and diagnosis of malignant tumors

Matrix metalloproteinases (MMPs) play important roles in tumor cell proliferation and apoptosis and contribute to tumor growth, angiogenesis, migration, and invasion primarily via extracellular matrix (ECM) degradation and/or the activation of pre-pro-growth factors. Recently, there has been considerable interest in the posttranscriptional regulation of MMPs via microRNAs (miRs). In this review, we highlight the complicated interactive network comprised of different MMPs and their regulating microRNAs, as well as the ways in which these interactions influence cancer development, including tumor angiogenesis, growth, invasion, and metastasis. Based on the conclusive roles that microRNAs play in the regulation of MMPs during cancer progression, we discuss the potential use of microRNA-mediated MMP regulation in the diagnosis and treatment of tumors from the clinical perspective. In particular, microRNA-mediated MMP regulation may lead to the development of promising new MMP inhibitors that target MMPs more selectively, and this approach may also target multiple molecules in a network, leading to the efficient regulation of distinct biological processes relevant to malignant tumors. A thorough understanding of the mechanisms underlying microRNA-mediated MMP regulation during tumor progression will help to provide new insights into the diagnosis and treatment of malignant tumors.

STAT3 upregulates miR-92a to inhibit RECK expression and to promote invasiveness of lung cancer cells

Background:

Signal transducer and activator of transcription 3 (STAT3) activation is frequently found in human lung cancer and is associated with increased metastasis and reduced survival. How STAT3 enhances invasiveness is unclear.

Methods:

The expression of microRNAs and target genes was measured by real-time RT–PCR. Protein level was studied by western blotting. Luciferase reporter assay was used to confirm the direct targeting of microRNAs. Gelatin zymography was used to study matrix metalloproteinase (MMP) activity. Transwell assay was used to investigate cell migration and invasion.

Results:

Enforced expression of STAT3 decreases the endogenous MMP inhibitor RECK protein but not mRNA level in H460 cells. Conversely, STAT3 inhibitor S3I-201 increases RECK protein in STAT3-activating H1299 cells. We demonstrate that STAT3 upregulates miR-92a to repress RECK via post-transcriptional inhibition. The RECK 3′-untranslated region (3′UTR) reporter activity assay suggests that RECK is a direct repression target of miR-92a. Delivery of pre-miR-92a reduces RECK protein level whereas transfection of anti-miR-92a restores STAT3-induced downregulation of RECK. Anti-miR-92a attenuates MMP activity, migration and invasion of H1299 cells and STAT3-overexpressing H460 cells, suggesting miR-92a is critical for STAT3-induced invasiveness.

Conclusion:

The STAT3-induced miR-92a promotes cancer invasion by suppressing RECK and targeting of the STAT3/miR-92a axis may be helpful for cancer treatment.

MicroRNA-222 promotes tumorigenesis via targeting DKK2 and activating the Wnt/β-catenin signaling pathway

MiR-222 in glioma can regulate cell cycle progression and apoptosis. However, the relationship between miR-222 and Wnt/β-catenin signaling pathway in glioma remains unknown. Here, we found that the Dickkopf-2 gene (DKK2) was a direct target of miR-222 by target prediction analysis and dual luciferase reporter assay. RNA interference silencing of DKK2 proved that miR-222 overexpression led to constitutive activation of β-catenin through inhibition of DKK2 expression in glioma cells. Furthermore, miR-222 siRNA significantly inhibited tumorigenesis in vivo. Finally, Western blot analysis showed that miR-222 could regulate the expression of β-catenin and the downstream genes of Wnt/β-catenin signaling pathway. Taken together, our findings reveal a new regulatory mechanism of miR-222 and suggest that miR-222 might be a potential target in glioma therapy.

The role of microRNAs in cancers of the upper gastrointestinal tract

Cancers of the oesophagus, gastro-oesophageal junction and stomach (upper gastrointestinal tract cancers; UGICs) pose a major health risk around the world. Collectively, the 5-year survival rate has remained <15%, and therapeutic improvements have been very slow and small. Novel molecules for early diagnosis, prognosis and therapy are, therefore, urgently needed. The role that microRNA (miRNA) molecules have in UGICs are worth pursuing to this end. miRNAs are small noncoding RNA molecules that regulate ∼60% of coding genes in humans and, therefore, are pivotal in mediating and regulating many physiologic processes. miRNAs are deregulated in many disease states, particularly in cancer, making them important targets. Here, we review the growing body of evidence regarding the alterations of miRNAs in UGICs. By suppressing translation and/or promoting degradation of mRNAs, miRNAs can contribute to carcinogenesis and progression of UGICs. In-depth studies of miRNAs in UGICs might yield novel insights and potential novel therapeutic strategies.

MicroRNA-182-5p promotes cell invasion and proliferation by down regulating FOXF2, RECK and MTSS1 genes in human prostate cancer

Recently miR-182 has been reported to be over-expressed in prostate cancer (PC) tissues, however detailed functional analysis of miR-182-5p has not been carried out. The purpose of this study was to: 1. analyze the function of miR-182-5p in prostate cancer, 2. assess its usefulness as a tumor marker, 3. identify miR-182-5p target genes in PC, 4. investigate the potential for miR-182-5p inhibitor to be used in PC treatment. Initially we found that miR-182-5p expression was significantly higher in prostate cancer tissues and cell lines compared to normal prostate tissues and cells. Moreover high miR-182-5p expression was associated with shorter overall survival in PC patients. To study the functional significance of miR-182-5p, we knocked down miR-182-5p with miR-182-5p inhibitor. After miR-182-5p knock-down, prostate cancer cell proliferation, migration and invasion were decreased. We identified FOXF2, RECK and MTSS1 as potential target genes of miR-182-5p using several algorithms which was confirmed by 3’UTR luciferase assay and Western analysis. Knock-down of miR-182-5p also significantly decreased in vivo prostate tumor growth. In conclusion this is the first report documenting that over-expression of miR-182-5p is associated with prostate cancer progression and potentially useful as a prognostic biomarker. Also knock down of miR-182-5p in order to increase expression of tumor suppressor genes FOXF2, RECK and MTSS1 may be of therapeutic benefit in prostate cancer treatment.

Discrimination of gastric cancer from normal by serum RNA based on surface-enhanced Raman spectroscopy (SERS) and multivariate analysis

PURPOSE

Here, the authors explore the feasibility of discriminating cancer patients from healthy controls by serum RNA detection based on surface-enhanced Raman spectroscopy (SERS) and multivariate analysis.

METHODS

MgSO(4)-aggregated silver nanoparticles (Ag NP) as the SERS-active substrate presented strong SERS signals to RNA. SERS measurements were performed on two groups of serum RNA samples: one group from patients (n = 31) with gastric cancer and the other group from healthy volunteers (n = 34).

RESULTS

Tentative assignments of the Raman bands in the normalized SERS spectra demonstrated that there are differential expressions of circulating RNA between the gastric cancer group and the control group. Principal component analysis (PCA) combined with linear discriminate analysis (LDA) was introduced to differentiate gastric cancer from normal and achieved sensitivity of 100% and specificity of 94.1%.

CONCLUSIONS

This exploratory study demonstrated potential for developing serum RNA SERS analysis into a useful clinical tool for noninvasive screening and detection of cancer.

Pathogen-driven gastrointestinal cancers: Time for a change in treatment paradigm?

The regulation of cancerous tumor development is converged upon by multiple pathways and factors. Besides environmental factors, gastrointestinal (GI) tract cancer can be caused by chronic inflammation, which is generally induced by bacteria, viruses, and parasites. The role of these inducers in cancer development, cell differentiation and transformation, cell cycle deregulation, and in the expression of tumor-associated genes cannot be ignored. Although Helicobacter pylori activates many oncogenic pathways, particularly those in gastric and colorectal cancers, the role of viruses in tumor development is also significant. Viruses possess significant oncogenic potential to interfere with normal cell cycle control and genome stability, stimulating the growth of deregulated cells. An increasing amount of recent data also implies the association of GI cancers with bacterial colonization and viruses. This review focuses on host-cell interactions that facilitate primary mechanisms of tumorigenesis and provides new insights into novel GI cancer treatments.

Down-regulated miR-625 suppresses invasion and metastasis of gastric cancer by targeting ILK

Accumulating evidence has shown that microRNAs are involved in multiple processes in cancer development and progression. Here, we report that expression of miR-625 is significantly down-regulated and negatively correlated with lymph node metastasis in gastric cancer. miR-625 significantly inhibits invasion and metastasis of gastric cancer cells both in vitro and in vivo. Moreover, we identify that ILK is a direct target gene for miR-625 and knockdown of ILK has a phenocopy of overexpression of miR-625. Taken together, our findings suggest that miR-625 plays an important role in the mechanism of tumor metastasis.